Process for agglomeration

ABSTRACT

A PROCESS FOR AGGLOMERATION OF POWDERS, ESPECIALLY SOLUBLE COFFEE, INVOLVING THE USE OF UPPER AND LOWER JETS OF STEAM WHICH IMPINGE AGAINST AT LEAST ONE FALLING CURTAIN OF POWDER AT A SUBSTANTIAL ANGLE SO AS TO DISRUPT SAID CURTAN INTO AGGLOMERATES WHICH ARE THEN WETTED AND REDIRECTED INTO A DRYING ZONE. THE PURPOSE OF THE UPPER JETS OF STEAM IS TO FORM AGGLOMERTATES OF VARYING SIZE, DENSITY, AND MOISTURE CONTENT WHEREAS THE PURPOSE OF THE LOWER JETS OF STEAM IS TO FURTHER WET THE AGGLOMERATES AND RENDER THEM MORE UNIFORM IN DENSITY, SIZE AND MOISTURE CONTENT WHILE INSURING THAT ALL OF SAID AGGLOMERATES ARE PROJECTED INTO THE DRYING ZONE. THE APPEARANCE OF THE RESULTING AGGLOMERATES IS CONTROLLED BY VARYING THE GRIND   SIZE AND PARTICLE SIZE DISTRIBUTION OF THE FEED POWDER MATERIAL.

April 16, 1974 SIENKIEWICZ ETAL 3,804,963

PROCESS FOR AGGLOMERATION Original Filed Dec. 26, 1967 4 Sheets-Sheet 1 v 25 I C'H/Zl-GK/NDER I H07 mgr Aw j 2 Wm r-DK/ED (05:55

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[ -mam RNA? Kin r15 April 16, 1974 a s NK ETAL 3,804,963

PROCESS FOR AGGLOMERATION Original Filed Dec. 26, 1967 4 Sheets-Sheet, 2

SIENKIEWICZ ETAL 3,804,963

PROCESS FOR AGGLOMERATION A ril 16, 1914 Original Filed Dec.

4 Sheets-Sheet 5 .1 QEP QRN .EQQMvQGQvW .Q 0 .r. .H H v April 16, 1974 B. SIENKIEWICZ ET AL PROCESS FOR AGGLOMERATION 4 Sheets-Sheet 4 Original Filed Dec. 26, 1967 AlEiiii m w m W w k ..&. m @Q Q? United States Patent 01 3,804,963 Patented Apr. 1 6, i974 Int. Cl. A23f 1/08 US. Cl. 426-453 4 Claims ABSTRACT OF THE DISCLOSURE A process for agglomeration of powders, especially soluble coffee, involving the use of upper and lower jets of steam which impinge against at least one falling curtain of powder at a substantial angle so as to disrupt said curtain into agglomerates which are then wetted and redirected into a drying zone. The purpose of the upper jets of steam is to form agglomerates of varying size, density, and moisture content whereas the purpose of the lower jets of steam is to further wet the agglomerates and render them more uniform in density, size and moisture content while insuring that all of said agglomerates are projected into the drying zone. The appearance of the resulting agglomerates is controlled by varying the grind size and particle size distribution of the feed powder material.

This is a continuation of application Ser. 'No. 43,310 filed Apr. 23, 1970, and now US. Pat. 3,695,165, which, in turn, is a division of application Ser. No. 693,503 filed Dec. 26, 1967, and now US. Pat 3,554,760.

.BACKGRQNND' OF THE INVENTION This invention relates to an improvement in the art of agglomerating powders according to the technique described in Sienkiewicz et al. 2,977,203 wherein a falling curtain 'of powder is projected in a horizontal direction while being wetand agglomerated and, more-particularly,

to an'improvement in the "art of agglomerating coffee by the fusion technique first described is co-pending Ser. No.

528,770, filed Feb. 21, 1966, in the names of Billy Kan and Saul N. Katz.

In the Kan et al. application, a process is described for forming strong coffee agglomerates (as distinguished from the weak coffee aggomerates of the prior art) by raising the temperature of the wet coffee agglomerates to above the fusion point of the coffee solids thereby,in effect forming at least partially melted or fused coffee agglomerates as distinguished from a merely dried solution of dissolved coffee solids in agglomerate form. Fusion of the coffee agglomerates is accomplished by increasing the moisture content at the surface of the coffee particles during agglomeration. Kan et al. stressed that the increase in moisture is necessary to lower the fusion or thermo- SUMMARY OF THE INVENTION It has now been discovered that a process and apparatus can be provided for producing relatively strong agglomerates of powdered material, such as coffee, bydropping a vertical curtain of powder into a steam zone where it can be disrupted into wet agglomerates'and redirected in a horizontal direction into a drying zone by having upper and lower jets of steam positioned in this steaming zone at a substantial angle to the falling curtain of powder. The function of the upper steam jet or jets is to disrupt the falling curtain of powder into wet agglomerates of varying size, density and moisture content'whilefthe function of the lower jet or jets of steam involves making the wet agglomerates more uniform in size, density and moisture content. The upper and lower jets of steam can -be adjusted according to known variables (angles,'pressure, temperature, steam-powder feed ratio, etc.)-in order to achieve optimum conditions whereby the lower jet or jets of steam act chiefly on the undesirable or weaklyformed agglomerates formed by the upper jet or jets of steam to thereby greatly improve the yield of strong agglomerates in the desired particle size range. By controlling the initial particle size (pre-grinding),'moisture content and temperature (pre-chilling) of the powdered material to be agglomerated, agglomerates can be achieved with predetermined properties in regard to density, color, flowability, strength, and particle appearance.

In the case of soluble coffee powder, it has been found that agglomerates of increased strength and more uniform size can be achieved by agglomerating said coffee under conditions whereby 28% of added moisture is distributed uniformly on the surfaces of the agglomerated particles to give a surface moisture as high as 10-15%, while the average moisture content may be only 510% and then fuse these agglomerates at a product temperature of below 250 F., say between 100 to 200 F. by contact with hot air having an inlet temperature of between 300 and 600 F. The high moisture content at the surfaces of the coffee agglomerate enables fusion to occur at lower product temperatures while avoiding flavor degradation by preventing the temperature of the product from exceeding the wet bulb temperature of the drying air. The fused agglomerates can then be dried at milder temperatures of 150 to 300 F. without hurting coffee flavor. This process is made practical by the use of upper and lower-steam jets which operate at steam pressures of 5-30 p.s.i.g. to form properly wet agglomerates at a steam to powder ratio in pounds per hour of between 0.421 to 1.2:1. Pregrinding, prechilling, and use of a vibratory feed box providing parallel, spaced sheets to the upper and lower jets of steam are all used to advantage in assuring a high moisture suitable for fusion-agglomeration of the coffee when contacted with hot air. The fused-agglomerates then require only 'a'drying step under milder air temperature followed by post-cooling to set the warm agglomerates and prevent caking. j

The use of higher initial moistures in the powdered coffee feed enables relatively high inlet temperatures to be plastic point of the coffee to a temperature range where fusion occurs without harming coffee flavor. This increase in surface moisture of the particles was accomplished by Kan et al. using steam to wet the coffee and then-maintained by using a humidified atmosphere for drying the coffee agglomerates, thus giving more time for the coffee to fuse'during drying. However, humidified air drying is difficult to use under commercial conditions and it would be desirable if a simpler or more practical method and apparatus were made available for obtaining fused coffee agglomerates.

used which would normally hurt the flavor of soluble coffee. Thus, while coffee with a normal moisture of 2- 3% cannot contact inlet air temperatures of above 500 'F. without some flavor degradation, if the coffee is prewet to about 5 6% moisture level or dried to this higher terminal moisture, it can then be contacted with inlet air temperatures of 500-600 F. giving rapid fusion of the agglomerates without danger of flavor degradation.

The apparatus for achieving these beneficial results are shown in the drawings and include the use of a vibrating feeder means having a series of parallel silts into which the coffee powder falls in a series of vertical parallel curtains which are then impinged by upper and lower steam jets I at a substantialangle in regard to the vertical plane of said curtains, the steam jets being released by steam pipes or nozzles arranged directly beneath the feeder means, the

' 1 to 20 from the horizontal and the plane of the steam I from the jets forms an angle of 70 to 80 with the falling curtain of powder at the point where thetwo streams meet while the lower jets are positioned slightly downvward to 30 from the horizontal) or slightly upward (0 to 10 from the horizontal).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of the agglomerating process -and the apparatus as used to form dried fused coffee agglomerates;

FIG. 2 is an enlarged side view of the upper and lower (double row) steam nozzles and the vibratory feeder showing the curtain of powder being contacted bythe v steam jets and projected into the agglomerating chamber.

FIG. 3 is a top plan view which shows the horizontal arrangement of the upper and lower row of steam nozzles relative to the parallel curtains of powder and shows the agglomerated particles being projected into the agglomeration chamber.

FIG. 4 is a still further enlarged perspective view showing the double row of steam nozzles and their arrangement in regard to the vibratory feeder.

FIG. 5 is a side view showing the typical trajectory of agglomerated particles as they are contacted by steam 1 from a single row of steam nozzles.

FIG. 6 is a side view which shows the trajectory of these agglomerates when using a lower jet of steam from a second row of nozzles directly beneath the first row of nozzles.

' DETAILED DESCRIPTION OF THE DRAWINGS Referring to FIG. 1, the full process of this invention will be described schematically in regard to coffee, al- 'though other powdered materials can be agglomerated by the same process and apparatus. Soluble coffee powder,

in the form of spray-dried coffee having an initial mois- "ture content of 2-4%, is first conditioned in chill-grinder 1 wherein the coffee is ground to a particle size of at least below 120 microns, and chilled to below 80 F.

Grinding increases the point-to-point contact of the coffee and is the major means of controlling product density and appearance since it has been found that as coffee is ground to a particle size distribution wherein substantially all particles are below 120 microns and at least 50% (by weight) are below 15 microns a speckled appearing product (which looks like roasted and ground coffee) is produced. At particle size distributions of below 120 microns, but at least 50% (by weight) of the particles are above 20 microns a nonspeckled product is obtained. At particle size distributions in between those recited, a product which is only partially speckled is obtained. Chilling aids uni-' formwetting of the coffee due to increase condensation of steam on the particles. Liquid nitrogen, CO or other "refrigerant can be used to chill the grinder 1. The conditioned coffee powder then enters a hopper 2 which has an ture in the range of 56%. This can be done by either pre-wetting the soluble coffee, by drying the soluble coffee to a higher terminal moisture in the drying stage, or by passing the soluble coffee through an agglomeration operation wherein coffee is not only prewet but agglomerated without being exposed to fusion or drying temperatures. The prewet coffee in either agglomerated or non-agglomerated form can then be used and dried by exposure to high inlet air temperatures without being degraded.

The conditioned coffee can be fed at a powder rate of roughly 30-60 lbs/hour per slit in the feed box while steam is supplied at a rate of -125 lbs/hour per nozzle used. The total powder rate for an agglomerating chamber 30 can vary depending on size and design of the unit and may be adjusted to give a steam:powder ratio of about 0.421 to 12:1, preferably 0.6:1 to 1.0:1. At higher steam ratios too much moisture is applied to the product and the drying air (thus hurting drying capacity) while at lower steam ratios good wetting of the coffee is not achieved (forming weak agglomerates). Steam at the above rate can be supplied to the double row of nozzles at a pressure of 5 to 30 p.s.i.g., preferably 8-20 p.s.i.g. Higher steam pressures (above 35 p.s.i.g.) cause excessive shearing action thus hurting agglomerate formation while lower steam pressures (below 5 p.s.i.g.) will not redirect or sufiiciently disrupt the falling curtain of powder.

Steam from the upper nozzles 10 interacts and disrupts the curtains of coffee powder to form agglomerates 24, some of which are desired in the process and others which are less desirable. The second row of steam nozzles 20 positioned directly underneath, preferably in front of the first row of nozzles, serve to project the wet agglomerates and, more importantly, serve to break up and further wet the large, insufficiently wet, weak agglomerates formed by the first steam pipe. All the agglomerates 24 are then projected a sufficient distance into agglomerating chamber 30.

The agglomerating chamber 30, which may be round or rectangular in design and of sufficient diameter and height to allow for both fusion and drying of the particles in said chamber is supplied with hot air for fusing and drying the agglomerates. Typically, the chamber 30 is at least 7 feet in diameter to avoid plastering of the walls and at least 20 feet in height to allow sufficient drying time for the falling particles to dry.

For a chamber of 12 feet in diameter and 30 feet in height and an initial moisture content in the powder feed of 2-4%, heated air can be equipped at 400 to 600 F. and a rate of 2,000 to 5,000 c.f.m. from hot air inlet chamber 25 via a center duct 26 and via duct 27 which feeds heated air into plenum chamber 28. The proportion of air coming through center duct 26 and duct 27 can be adjusted by a damper (not shown). A majority of the heated I air (now at a temperature of 350 to 500 F.) comes out center duct 26 and contacts the wet agglomerates which have been projected into the agglomerating chamber along with a substantial draft of ambient airfrom outside of the chamber- (which serves to lower the temperature of the hot air from duct 26). The advantage of the center duct 26 is that it allows hot air, at a relatively high temperature suitable for fusion, to be introduced into the middle of the chamber after the agglomerates have had a chance to besufiicient wet (and fusion has been initiated) by the double row of steam nozzles. If enough hot air at above 350 F. is introduced adjacent the steam zone, it evaporates and dries the steam auger feed 3 driven by motor 4 supplying vibratory trough .5 with a constant stream of coffee powder which is transferred into a distributor box 6 having parallel slits therein coffee can enter the chill grinder 1 at a higher initial moisbefore it sufiiciently wets the coffee agglomerates to a point sufficient for fusion. However, some air, sayl0%- 50%, can be introduced through holes 29 in the plenum 28 so that a co-current flow of heated air with thewet agglomerates 24 is formed inside chamber 30. The agglomerates are fused at a product temperature of to 250 F. due to the combined action of the hot steam and the agglomerates after fusion.

heated air giving a temperature of about 300to' 500 F. in the upper 'one half portion of chamber 30. The particles are then dried as they fall through the chamber by gravity in a co-current pattern with the drying air which exits through exhaust duct 32 at a milder drying temperature of 150 F. to 300 F., due to the action of exhaust I and easier fusion of the product and a stronger, darker agglomerate. However, with the usual powder feed (at 2-4% moisture) the wet agglomerates cannot be exposed "to inlet air temperatures above 500-525 F. since the air then dries the surface moisture too rapidly and hurts the flavor of the coffee while at inlet air temperatures below "300 F. it is quite difficult to obtain any substantial amount of fusion.

' Removal of dried agglomerates with the exhaust air'is minimized due to battle 31a whichextends in a downward direction into exhaust duct 32. Exhaust air exits from the dryer at a rate sufficient to maintain the above dryer conditions with a slight negative pressure in the chamber 30.

-The dried agglomerates contact wall 33 which is relatively cool and then fall through discharge duct 34 intoa cooling tunnel 40. There is some inlet of'cold air through -"duct 34 into the bottornof chamber 30 which can vary from 800 to 1,500 c.f.m., usually LOGO-1,200 c.f.m.

Cooling tunnel 40 employs a conveyer for carrying the warm agglomerates 24 in a thin bedwhich is cooled by a-forced draft of cold air which enters inlet" 41 "and exits through outlet 42. This cooling step is necessary in order size distribution. Oversized agglomerates'are removed and further ground in mill 46 and then combined'with'the product in container 45. Agglomerateswhich are too small (fines) are removed and used as recycle material for the chill-grinder along with the -fines removed by'the exhaust airinduct32.'

I Referring nOW to FIG. 2, the'vibratory feeding means 'andthe steam jets are'shown in more detail. The chilled and ground coffee (ground to a size which will give either a speckled or nonsp'eckled product) falls through slits in the box 6 as a series of vertical parallel curtains which are contacted by steam jets which impinge against the curtains at a substantial angle as more fullydescribed in US. Pat. 2,977,203. It is understoodthat in lieu of a box with slits,

-"',a box with a screen could be used and a slit arrangement achieved by soldering or-sealing alternate rows in the screen. 'Inthepresent embodiment, the upper row of steam pipes 11 and nozzles are slanted in a slight downward angle (say 10 to from the horizontal plane) in order to achieve" disruption of the curtain into agglomerates which are then wet with a minimum of horizontal projection of the agglomerates. Projection and further wetting of the moistened agglomerates 24 is left to the lower row of steam pipes 21 disposed at a slight upward angle (say about 5 to 10 with respectto the horizontal). The sec- 0nd row of steam nozzles 20 acts not only to project the agglomerates (which are merely clumps of dry coffe'ewet at" the surface) formed by the steam from the first row of nozzles 10 and which, upon'dr-ying, would form weak agglomerates but also serves to breakup-and further wet these clumps, thus giving stronger agglomerates. v

' FIG. 3 is a top plan view which shows the trajectory of the agglomerates 24 looking 'do wnward on "the vertical parallel curtains23 (formed'by the parallel slits inthe bottom wall 8 of the distributor box 6) as the curtains" are contacted by the steam jets from the double row of "steam pipes (upper row 11 and lower row 21). In this "embodiment, the upper row has two steam pipes 11 with two steam nozzles 10 placed above a lower row of three steam pipes 21 having three steam nozzles 20 but the number of nozzles and slits can be increased proportionately depending on the capacity desired. The falling cur- "tain 23 of coffee powder is disrupted by the horizontally directed steam jets released by the upper and lower nozzles 10 and 20 and the wet agglomerates 24 formed are projected into chamber 30 for fusion and drying.

The relative arrangement of the vibrating trough 5, the distributor box 6 and the double row of steam pipes,

" shown in FIGS. 1-3, can be seen perspectively in FIG. 4.

In this view, the parallel slits 9 having a preferable dimension of /s inch wide openings are shown in bottom wall 8 although narrower slits A inch wide) and wider slits inch wide) work almost as well with some sacrifice in capacity on wetting, respectively. The steam for both nozzles 10 and 20 may be supplied from a common source or from different sources and may be at the same pressure or under different pressure, depending on the'particular system employed. Also, the particular angle of the upper row of nozzles 10 and the bottom row of nozzles 20 can be varied as long as the nozzles are at a substantial angle with respect to the direction of travel of the curtain of powder and as long as steam issuing from the jets can be considered to be traveling in the same plane as the curtain of falling powder as described in the Sienkiewicz et al. patent. The second row of nozzles are usually positioned at a slight upward angle and serve to project agglomerates already wet by the first pipe while further wetting these agglomerates and also serves to shear or disrupt large, dry agglomerates into smaller, better wet agglomerates. The top row of nozzles are set low enough (at a downward angle) to prevent wetting the bottom of the feed box. If they are set too low, the'steam hits the curtains of powder from the feed box at a point where the curtains begin to spread and lower density, weaker agglomerates are formed. If the nozzles are set back too far, the velocity of the steam is spent before it hits the curtains of powder and the agglomerating effect is lost, the powder falls through the steam and is not conveyed into the steam jet. This results in poor wetting and insufiicient agglomeration. The angle of the steam pipe can be varied slightly to decrease the horizontal trajectory of the agglomerates.

7 ,Referring now to 'FIGS. 5 and 6, the advantages of the double row steam agglomeration of this invention will be more fully realized. FIG. 5 is a sketch which represents the approximate trajectory of the particles which are agglomerated according to the single pipe principle of US.

Pat. 2,977,203. It will be noted that the coffee powder is fedby a vibratory trough 5a into a distributor box 6a which is vibrated by air vibrator 7a. Coffee powder can be seen to fall in a vertical curtain 23a which is then contacted by a single jet of steam from nozzle 10a. The jet of steam can be considered to be in the same plane as the falling curtain 23a and intercepts the falling particles at a; substantial angle to the direction of travel of said particles to agglomerate the particles and redirect the :particles in substantially the same plane.

;These particles fall in a short trajectory or relatively "vertical path between the 1 and the 3 mark. The second type of agglomerate D is smaller in size and sufficiently wet and can be classified as being a desirable agglomerate in appearance, bulk density and strength. These particles will follow a trajectory which is less vertical and will fall somewhere between the 3' and 8' mark. The third type of agglomerate C is smaller, is sufficiently wet and strong and is projected the greatest distance. This ag'glomerate C follows a trajectory which falls between the 8 and 10' mark. It is understood that FIG. 5 is a pictorial description which simplifies the agglomeration operation for description purposes and that the large, medium and small agglomerates are actually distributed in some part throughout the entire trajectory scale. Also, the trajectory will change with the angle of the steam jets, their pressure, the powder feed, and other variables. In all cases, however, the particle size distribution with a single steampipe (or row of steampipes) and a single curtain of powder (or a plurality of curtains) will be the same in that heavy agglomerates insufficiently wet will fall first, followed by the medium agglomerates, and then followed by the smallest agglomerates.

Now, referring to FIG. 6 where a second steam nozzle 20a is placed beneath the first steam nozzle 10a, it can be seen that the agglomerates A, B and C are formed (as in FIG. 5) by the first steam jet disrupting the curtain and further acted upon by the second steam jet from nozzle 20a and that the steam from this nozzle serves not only to further wet the particles but serves to breakup or shear the large, dry agglomerates A which would form defective agglomerates on drying due to insufficient wetting of the coffee powder inside the agglomerates. These large agglomerates are broken up into smaller agglomerates A. In other words, the second steam nozzle 20a is disposed below the first steam nozzle 10a and in front of the nozzle 10a to contact a maximum of the agglomerates formed by the steam from the first'nozzle. The large agglomerates A will now be broken up into small agglomerates A and further wetted in order to give a stronger agglomerate on drying. This is due to better wetting of the agglomerate, thus enabling better fusion of the agglomerate in the drying chamber. The smaller agglomerate A will be distributed throughout the agglomerate trajectory and will be mixed with the smaller agglomerates B which have been properly formed by the steam from nozzle 10a. As to agglomerates B, the lower steam jet from nozzle 10a only serves to further wet these particles to enable better fusion of these agglomerates B during their trajectory. As to the smaller particles C, the second steam jet has little effect on these agglomerates except for some further wetting of the particles for better fusion during the trajectory of these particles. Here also, the same trajectory of particles A, B, C, A, B and C is involved whether one curtain 23a of powder is contacted by an upper steam nozzle 10a and a lower steam nozzle 20 or a plurality of vertical curtains similar to23a are contacted by a number of nozzles similar to 10a in a single row followed by contact with a second row of nozzles similar to 20a.

DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention will now be described by reference to several specific examples which show the production of fused coffee agglomerates dried to a uniform size and density in accordance with this invention.

EXAMPLE 1 Soluble coffee powder (obtained by spray-drying conventional coffee percolate with a solids content of 2 5- 35%), having a particle size distribution of between100 200 microns, a moisture content of about 2.5% and a density of 0.18 gm./cc., was ground in a hammer mill of the Fitzpatrick type shown as a chill grinde'r'l' in the FIG. 1 drawing. During grinding, the powder was chilled by admission of liquid C0: to the grinding chamber, the liquid CO cooling the chamber and powder as it sublimed. The powder left the chill grinder at a temperature close to 35 F. and particle size distribution wherein 100% of the particles were smaller than 100 microns, at least by weight, were smaller than 50 microns, and at least 50% of the particles were therefore above 20 microns. The ground powder which now had a much lighter color than the starting material entered hopper 2 and was distributed by auger feed 3 onto the vibrating trough 5.

The ground and chilled powder which now had increased, slightly in moisture content (to about 2.7% moisture) due to condensation and had a density of 0.50 gm./cc. was then fed into the vibrating box 6 having dimensions of about 12" in length, 5" in width and a height of about 4", the box being equipped with 13 narrow slits A" wide and 2" long spaced about /2" from one another in a parallel relation. The chilled powder dropped by gravity through the parallel slits in the form of 13 parallel curtains dropping in a vertical direction or plane until redirected by the first steam jets from nozzles 10 and 20. The powder was fed at a rate of about 500 lbs/hour or roughly about 40 lbs/hour per slit while the steam was adjusted to achieve a 1:1 ratio of powder to steam by having each nozzle deliver about lbs. of steam per hour. The first series of steam jets had a nozzle pressure of 14-16 p.s.i.g. and the steampipe was disposed at a downward angle of about 15 with respect to the horizontal plane, whereas the second steam pipe with nozzle 20 was disposed below the first row nozzles 10 and slightly forward of these nozzles at an angle of about 7 with respect to the horizontal. The second series of steam jets had a pressure of about 12 p.s.i.g. The falling powder was agglomerated into agglomerates of different size, density and moisture content by the first series of jets and then further wet, redirected and made more uniform in density, size and moisture content by the second series of jets which assured that all of the .wet agglomerates were redirected and projected about 5 to 8 feet into the middle of the agglomerating chamber 30 where the wet .agglomerates were contacted by the inlet air (heated to 400 to 450 F.) and a minor amount of air through plenum chamber 28 and openings 29 serving to establish a co-current flow of heated air (at a rate of 2500 c.f.m.) which assured fusion of the agglomerates 24 in the upper portion of the chamber prior to their being dried as the agglomerates fall a distance of at least 20 feet before contacting the relatively cool bottom walls 33 andexiting through duct 34 onto the conveyer belt 43 of the coolingtunnel. The drying air exited through duct 31 at a temperature of 260 to 280 F. and some cold airfrom the tunnel was sucked into the chamber at a rate of about 1000 c.f.s. The warm agglomerates were further chilled by the cold air (50 F.) which entered through bottom duct 41 and exited through exhaust 42. The set agglomerates were then passed through a screen 44 to achieve a particle size distribution of between 540 mesh U,.S. Standard Sieve with at least 50% of the particles being mesh (US. Standard Sieve). The 15% mesh fraction was ground inmill 46 and added to the .above while thefines fraction was recycled.

EXAMPLE 2 ,The process of Example 1 was followed with the exception that the coffee powder was ground to a size distribution of 100% less than 60 microns and at least 50% less than 15 microns.

This product had the same characteristics as the Example 1 product with the exceptions that this product was of slightly higher density (0.24 gm./cc.) and speckled in appearance.

9 EXAMPLE 3 The procedure of Example 1 was followed with the exception that the inlet air was 600 F. and the coffee powder (after being ground in the chill-grinder) was prewet to a moisture content of 6% by blending the coffee with finely ground ice.

This product was nonspeckled, uniformly darker in color than the Example 1 product, and, more significantly, showed added agglomerate strength when subjected to packaging and shipping tests.

EXAMPLE 4 The procedure of Example 3 was repeated with the exception that the coffee was not chilled during grinding.

The same product as in Example 3 was obtained.

EXAMPLE 5 The procedure of Example 1 was followed with the exception that the coffee powder obtained from the spraydrying tower was dried to below 1.5% moisture. The product was ground in the chill-grinder and then agglomerated.

This product was nonspeckled, lighter in color, but extremely weaker in agglomerate strength when subjected to packaging and shipping tests. The strength of these agglomerates was only slightly stronger than the nonfusion control of Example 1.

EXAMPLE 6 The procedure of Example 1 was repeated with the exception that air was introduced from the sides of the chamber 30 instead of the top of the chamber at a position about feet below the steam and agglomeration zone. At least 20 feet was allowed for drying of the agglomerates.

The product characteristics of these agglomerates were the same as the Example 1 product.

EXAMPLE 7 The procedure of Example 1 was repeated with the same apparatus except that an additional steam agglomerator (composed of a box feeder 6 and steam noule 10 and 20) was placed on the opposite side of the chamber. Capacity was almost doubled by control of known variables.

The strength of the agglomerates over a control sample prepared under non-fusion conditions was shown by machine packaging of the product in jars and then subjecting the jars to shaking tests. Product prepared according to this example retained its agglomerate form whereas the nonfusion product did not.

While this invention has been described by reference to several specific embodiments, it is intended to be limited only by the scope of the appended claims.

What is claimed is:

1. In a process for producing dry, speckled, free-flowing agglomerates of soluble cofiee powder, the improvement which comprises:

(a) grinding the soluble coffee powders to a particle size of at least below 120 microns and a particle size distribution wherein greater than 50% by weight of the powder is below microns, and

(b) agglomerating the ground powder.

2. In a process for producing dry, speckled, free-flow ing agglomerates of soluble coffee powder, the improvement which comprises:

(a) grinding the soluble cofiee powder to a particle size of at least below 120 microns and a particle size distribution wherein greater than 50% by weight of the powder is below 15 microns, and

(b) agglomerating the ground powder by dropping said powder in the form of a continuous vertical curtain into a steam zone which forms wet agglomerates by horizontal redirection into a drying zone, said steam zone effected by introducing upper and lower jets of steam disposed at a substantial angle to one side only of said vertically moving curtain of powder at a steam pressure suflicient to form wet agglomerates, said upper jet of steam disposed at an angle sufficient to disrupt said curtain into wet agglomerates of varying size, density and moisture content and said lower jet of steam disposed below said upper jet of steam at an angle sufiicient to further wet and redirect said wet agglomerates with a force sufiicient to render the size, density and moisture content of said agglomerates more uniform, said lower jet redirecting the wetted agglomerates through an un obstructed space on the side of the powder curtain opposite to the steam jets, said redirected agglomerates then falling through a drying zone, hot air in said drying zone being circulated to reduce the moisture content of said wetted agglomerates.

3. In a process for producing dry, uniformly colored, free-flowing agglomerates of soluble coffee powder, the improvement which comprises:

(a) grinding the soluble coffee powder to a particle size of at least below microns and a particle size distribution wherein greater than 50% by weight of the powder is above 20 microns, and

(b) agglomerating the ground powder.

4. In a process for producing dry, uniformly colored, free-flowing agglomerates of soluble coffee powder, the improvement which comprises:

(a) grinding with soluble cofliee powder to a particle size of at least below 120 microns and a particle size distribution wherein greater than 50% by weight of the powder is above 20 microns, and

(b) agglomerating the ground powder by dropping said powder in the form of a continuous vertical curtain into a steam zone which forms wet agglomerates by horizontal redirection into a drying zone, said steam zone effected by introducing upper and lower jets of steam disposed at a substantial angle to one side only of said vertically moving curtain of powder at a steam pressure suflicient to form wet agglomerates, said upper jet of steam disposed at an angle suflicient to disrupt said curtain into wet agglomerates of varying size, density and moisture content and said lower jet of steam disposed below said upper jet of steam at an angle suflicient to further wet and redirect said wet agglomerates with a force suflicient to render the size, density and moisture content of said agglomerates more uniform, said lower jet redirecting the wetted agglomerates through an unobstructed space on the side of the powder curtain opposite to the steam jets, said redirected agglomerates then falling through a drying zone, hot air in said drying zone being circulated to reduce the moisture content of said wetted agglomerates.

References Cited UNITED STATES PATENTS 1/1971 Sienkiewicz et al 99-71 l2/ 1969 Adler et al. 99DIG 4 1/1969 Kan et al 99DIG 4 2,977,203 3/1961 Sienkiewicz et al. 99DIG 4 2,832,686 4/1958 Louder et al. 99-*DIG 4 TIM R. MILES, Primary Examiner W. L. MENTLIK, Assistant Examiner NITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,804,963 1 Dated April 16, 1974 Inventor(s) Boleslaw Sienkiewicz and Ferdinand A'. Ba'gley It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 39, "BACKGRONND" should read BACKGROUND co1.'l1, line 48, "and now u. s. Patent No. 3,424,589" was omitted after Saul N. Katz" line 321 of added moisture" should read -6% Of added moisture I Col. 3; line 14, "70 to 80" should read 70 to 89 Col. 4, line 29, "interacts" should read intersects v Col. 6, line 74, "agglomerate D" should read agglomerate B -1- Col. 8,- line 58, "120 mesh'f should read +20 mesh Col. 8, line 58, "15% mesh" should read +5% mesh Signed and sealed this 3rd day of December 1974.

(SEAL) Attest:

McCOY M. GIBSDN JR. C. MARSHALL DANN Attesting Officer Commissionerof Patents FORM PO-IOSO (10-69) v v Y USCOMWDC w ves V I a U.5. GOVERNMENT PRINTING OFFCE 2 I959 6-356-33 

